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> As for what an extra-terrestrial light sail would be doing in our solar system, Bialy and Loeb offer some possible explanations for that. First, they suggest

> As for what an extra-terrestrial light sail would be doing in our solar system, Bialy and Loeb offer some possible explanations for that. First, they suggest that the probe may actually be a defunct sail floating under the influence of gravity and stellar radiation, similar to debris from ship wrecks floating in the ocean. This would help explain why Breakthrough Listen found no evidence of radio transmissions. Wouldn't it be advantageous for Oumuamua's creators to simply collect data, leave the observed systems alone and start transmitting when those clueless Earthlings aren't listening anymore? This thing was noticed only at 0.25 AU _post_ flyby. It is sort of terrifying that someone might have sent this... Anyways, I am highly skeptical. For all we know, this was a slightly out-of-the-ordinary rock that swung by Sol. Our current inability to explain its behaviour due to lack of data immediately has people screaming "Aliens!". Well, one notable issue here is that the "Aliens!"-conclusion is not due to evidence for the fact (detected transmissions, clear artificial behaviour or surface structures) but lack of evidence against it. One natural cause for the acceleration when moving away from the Sun as well as the fast spin would be outgassing, but: > In addition, they cite other research that showed that if outgassing were responsible for the acceleration, it would have also caused a rapid evolution in 'Oumuamua's spin (which was not observed). Are we sure we didn't just fail to detect it? As nature would have it, improbable configurations might have been at work here and multiple streams of outgassing may have stabilised spin?

wallace_f 8y ago
>Are we sure we didn't just fail to detect it? I would be interested in knowing more about the possibility of that from people who study comets. The alternative theory is the object is an extremely thin sheet (0.3mm thick), which is what these scientists suggest as the best fit for the data. That would be a really thin slice of space rock.
- candiodari 8y ago
  How about from the people who study chance ? The issue with rare events is that you can never estimate the probability curves. This has the strange result that each one looks unique, complex and very much non-random ... despite potentially being very common, simple and random. We have one example from an unknown distribution. You can always read a lot into it's exact properties ... but there's nothing to be read, because we don't have the variation on those properties. So this could have been a very common run-of-the-mill interstellar asteroid ... and it could have been an alien explorer. We don't know, and we probably won't know. Well, I guess in the second case we'll eventually realize.
  - wallace_f 8y ago
    Good ideas. But what I meant was about the possibilities of outgas-propellent existing without them being observable.

wallace_f 8y ago

>Are we sure we didn't just fail to detect it? I would be interested in knowing more about the possibility of that from people who study comets. The alternative theory is the object is an extremely thin sheet (0.3mm thick), which is what these scientists suggest as the best fit for the data. That would be a really thin slice of space rock.

candiodari 8y ago
How about from the people who study chance ? The issue with rare events is that you can never estimate the probability curves. This has the strange result that each one looks unique, complex and very much non-random ... despite potentially being very common, simple and random. We have one example from an unknown distribution. You can always read a lot into it's exact properties ... but there's nothing to be read, because we don't have the variation on those properties. So this could have been a very common run-of-the-mill interstellar asteroid ... and it could have been an alien explorer. We don't know, and we probably won't know. Well, I guess in the second case we'll eventually realize.
- wallace_f 8y ago
  Good ideas. But what I meant was about the possibilities of outgas-propellent existing without them being observable.